The Best CO2 Regulators for a Stable Planted Aquarium

To have thriving aquarium plants at home you’ll need to supply them with carefully regulated amounts of Carbon Dioxide. In such setups, a dual-stage pressure-reducing valve is an advantage, though it’s not a necessity if you’re aiming for the best CO2 regulator for indoor aquarium use.

I will explain the importance of a number of components that make up this piece of equipment.

For instance, what’s a needle valve and what role does it play in the whole system? Is your unit’s choice tied to the size of your tank? What will suit a nano tank with aquatic plants and also the opposite – larger setups?

Obviously, your budget can also come into play when you buy, so is getting a unit that falls on the cheap side of pricing worth it?

You’ll also need to look for a timer that binds the release of Carbon Dioxide to the set photoperiod because that’s when plants utilize the compound. Following these thoughts, it’s obviously best if CO2 regulators have a solenoid valve which is a vital component when looking after successful high-tech planted aquariums.

Let’s begin.

Top 4 CO2 Regulator Units for a Planted Aquarium

Before we start, here’s a quick overview of the CO2 regulators that are currently best for aquarium use:

Regulator name: Decompression relief: Price bracket:
1. Fzone Aquarium Dual Gauge Single stage $
2. DoubleSun Double-gauge Single stage $
3. FZONE Triple Stage Triple stage $$
4. S.T. International Single stage $$$$

An A-to-Z guide on CO2 regulators and their role in home aquariums

Due to competition, different companies usually design the same product differently, coming up with new features or improving on old ones to have an edge.

It is the same case when it comes to CO2 regulators; they come in different shapes, sizes and with varying features.

It is up to you to decide what is optimal for your setup, but I will try to provide some helpful pointers.

Here is a complete guide to help you choose an appropriate CO2 regulator for your aquarium:

1. With or Without a Solenoid Valve

Aquarium plants need CO2 but only during the process of photosynthesis.

Photosynthesis occurs only in the presence of light, so if the light is off, much of the CO2 you inject into your aquarium goes to waste.

Here’s what a solenoid valve does in conjunction with an aquarium CO2 regulators:

A solenoid is a device that allows for control over the CO2 consumption in an aquarium while making the process incredibly efficient. A solenoid works with a timer that is connected to the aquarium lights. This way, when the lights go off the solenoid valve turns off the CO2 supply automatically.

If your CO2 regulator is without a solenoid, you always have to be physically available to turn off the CO2 regulator.

This is, in my opinion, a crucial part of a CO2 regulator for a healthy planted tank.

2.Needle Valves and how they impact the even delivery of Carbon Dioxide

Here’s what’s a needle valve and what role it plays in CO2 regulators for aquariums:

A needle valve is responsible for delivering the CO2 in the aquarium at an even pace. With one, you’ll be able to fine-tune the gaseous Carbon Dioxide release so that it doesn’t storm the fish tank and cause harm to its live inhabitants. The needle valve achieves this by further normalizing the pressure from the cylinder in accordance with the desired flow-rate of the CO2 bubbles.

Without such a valve, the CO2 may get violently pumped into the tank when the cylinder is near-empty.

This does not happen often, but it is possible, if you don’t refill the CO2 cylinder upon noticing a drop in its internal pressure.

This is so because when close to running out of CO2 the cylinder cannot maintain a high pressure inside.

Because of the difference in pressure, a regulator without a needle valve will compensate by sucking out all of the remaining CO2 in the cylinder and dumping it into the aquarium all at once, which in such doses can be fatal for fish or shrimp inside.

This phenomenon is also affected by the stage of pressurization control.

With a needle valve, your regulator is more efficient, and you can micro-control the CO2 flow rate, setting it to needle-sized bubbles that are being released at an even pace.

3. Single Stage Vs Double Stage Pressure Relief

As the liquefied CO2 in the cylinder decreases, the regulator’s delivery pressure tends to increase because the remaining bit is mostly in gaseous form, which exerts lower opposing pressure.

This can at times cause enough imbalance, leading to the “end of tank dump” phenomenon.

If an excess volume of CO2 ends up in your aquarium it can be fatal for fish and invertebrates alike.

So here is the role of dual or two-stage pressure relief in a CO2 regulator for a fish tank:

A dual-stage pressure relief valve ensures the output pressure from the cylinder remains constant as its content flows into the aquarium, even when the CO2 is in a gaseous state. A CO2 regulator with a double stage valve reduces the pressure twice, providing more precise control over the dump of Carbon Dioxide in the aquarium. In that regard, a single-stage CO2 regulator is not unreliable but will need more diligent supervision towards the end of the CO2 cylinder. If the pressure inside the bottle starts dropping and you have a single-stage regulator you’d want to refill the cylinder before it runs completely empty.

But how is this achieved and how exactly does a double-stage pressure relief work?

The pressure reduction is realized in two stages.

Both stages comprise a diaphragm, spring control valve.

In the first stage, the pressure is decompressed to three times lower than the cylinder pressure.

The same is further lowered in the second stage to a range you can easily control with the adjustment knobs.
On the other hand, a single-stage regulator tends to lose some control when the pressure gets higher as the cylinder nears depletion. In that case, more frequent adjustments are needed when the tank is near-empty.

If you are using a single-stage pressure relief, you need to be around to adjust the flow rate whenever necessary.

This is not as annoying and time-consuming as it sounds, because it won’t happen often.

Additionally, a single-stage regulator is safer and more reliable compared to a double-stage model.

I should also point out that the single-stage regulator beats the dual one on the price.


It should be pointed out that the EOTD (“end of tank dump”) is not something bound to occur whenever the CO2 cylinder is near-empty. This may or may not happen and actual reports of it are somewhat rare among users of pressurized CO2 systems with a single stage regulator.

It should be also noted that the most common choice of a CO2 regulator among hobbyist fishkeepers is a single-stage one.

That’s so because you can easily prevent EOTD events by monitoring the gauges on your regulator.

When the tank is full with liquid CO2 its internal pressure will be somewhere between 800 and 850 PSI.

When the pressure gets considerably lower than that (read, around 750 to 700) it’s time for a tank refill or replacement.

EOTD supposedly happens when the internal pressure has already dropped to around 500 PSI.

4. Easy-To-Read And Accurate Gauges

Obviously, some devices are not made for a layman, and the same can be said of some for the Carbon Dioxide regulators.

It’s not rocket science per se, but it can get confusing if you’re a beginner.

Fortunately, there are regulators with easy-to-understand gauges.

Here is what to consider when it comes to readability and accuracy while choosing a Carbon Dioxide regulator:

Go for a CO2 regulator you can always read and understand fast enough at a glance. If you have to think to figure out what is what, then the model you’re looking up is probably not for you. Readability is so important with these devices because the one operating them should be able to understand them and react in time when needed to avoid fish fatalities.

Also, if you have problems reading tiny fonts, make sure to buy a CO2 regulator with a font large enough for you to see clearly.

5. Durability & Build Quality

Basically, CO2 regulators are made to last but, as I have said, there are those competitive manufacturers who go the extra mile to design models that have tremendous durability.

Here are the materials that the most durable CO2 regulator are made of:

If a CO2 regulator is made of brass, aluminum, aluminum alloy, stainless steel or steel alloy, it can be a good sign that it is durable.

Know that more sturdy builds will come at a higher price, because of the materials used.

6. Pricing

At times, we all need to filter products based on their prices. After all, you only buy what you can afford.

Here is what to consider as you decide how much you want to spend on a CO2 regulator:

Take time to balance the price against the pros. A cheaper CO2 regulator may come with limited features or less durable materials.

That being said, the ones I’ve included below do have a decent amount of positive feedback and I’ve also tried a couple of them personally.

I made sure to only list ones that will serve you well, but that’s upon proper usage.

The tricky part here is that you need to know your device and use it as per the instructions of the manufacturer.

The products in this category are rather sensitive and improper usage can lead to malfunctions quickly.

A lower price does not necessarily reflect a build that won’t last, but rather how human-error-proof the device may be.

If you use your unit with care you’ll be able to provide it with a long life despite, say, the lower pricing.

7. Compatibility

While there is no single CO2 regulator that fits all cylinders, there are particular ones that agree with many.

Here is the obligatory reminder about a CO2 regulator’s compatibility with gas cylinders:

If you have many different types of CO2 cylinders that you’ll be interchanging, you should go for a CO2 regulator that is compatible with them. This will save you from having to buy various models of regulators. If you have only one CO2 gas cylinder, make sure the regulator you buy agrees with it to keep you from having to return it to the seller for the right one.

What’s The Best Carbon Dioxide Regulator For A Thriving Planted Tank?

To find the best type of CO2 regulator for your particular aquarium you’ll need to consider the advantages of a model and compare it to your personal preferences and goals.

The ones that I’ve reviewed here have either proven themselves to me personally or someone I know in real life.

I consider all of them to be worth their price tag.

Here are the best CO2 regulators for a thriving planted aquarium:

1. Fzone Aquarium Co2 Regulator Big Dual Gauge – Surprisingly Fair Priced

Click here to see the current price + more photos on Amazon.

First, I should probably take the time to mention this company’s customer care service.

In case of anything, you can always reach out to FZONE for speedy feedback.

I know how it feels when you buy from a company that cares little about you after you have purchased a product.

That said, the FZONE Big Double Gauge is one of the best performers in the field of CO2 regulators given its price tag and you should definitely consider it for your aquarium.

While comparatively cheap, this unit has all the necessary kits you should require of your future regulator.

First, it has solenoid (110v) which operates flawlessly once you have set it to a timer.

If you want an automatic overnight shutoff, you just program it and the solenoid valve does the rest.

The solenoid runs noiselessly though you may hear a humming sound if you over-tune your ears.

Fzone Aquarium Co2 Regulator Big Dual Gauge also comes with a wrench you are to use to tighten the unit to the tank, which is pretty handy. Another thing you will see in the package is the check valve to stop water in the bubble counter from draining into the CO2 cylinder.

In terms of looks, it has a decent appearance (I like the smooth touch of the knobs) and is made of high-quality aluminum alloy.

If used properly it should last you a decent amount of time, though it will not be the most durable unit on this list.

It is also easy to set up — you don’t need to be an expert.

Initially, the needle valve could be over-precise, therefore slightly hard to control.

This should not worry you.

In my experience you should just relax your fingers and adjust slightly by and by.

It’ll gradually pick up and behave.

You can set the customary three bubbles per second which in my book means it’s precise enough.

Anyway, I feel it should come with an instruction manual to help a newbie set it up.

It’s a single-stage model, but if you pay attention to when the pressure in the bottle drops and refill it in time you will not have any issues.

Buy this CO2 regulator if you’d like to get the best bang for your buck, while not breaking the bank for your new high-tech planted tank.

  • Several kits are in the package – a solenoid, a bubble counter and a check valve.
  • The price is more than fair.
  • The components are made of aluminum alloy.
  • The big dual gauge ensures you can easily read the pressure in the cylinder and the output pressure, which compensates for the single-stage pressure control.
  • It comes without instructions, though if you email the company they promptly send it.
  • Single stage (not really a problem, because the gauges are easy to read and you can be certain when it’s time to refill your CO2 bottle)

2. DoubleSun Double-gauge Aquarium CO2 Regulator – Comes with everything you need

Click here to see the current price + more photos on Amazon.

If you are on a budget and are interested in a cheaper option, it may serve your aquarium’s interests best if you choose this double-gauge CO2 regulator.

But cheaper should by no means insinuate that it is a substandard version of a quality regulator.

It injects CO2 as precisely as any other suitable model.

The bubble counter and the nut holding the regulator are made from plastic and not glass as is customary, but in my experience, it’s no big deal.

The solenoid valve temperature remains stable at pretty much all times.

The hotness is usual, nothing to be concerned about.

Actually, for me, I’d describe it as warm and not hot, if that means anything to you.

Some users do complain that the same solenoid makes a nagging humming sound.

In my experience with this regulator, this is true but only under certain circumstances.

In any case, I would not describe the sound as potentially irritating, but you will notice it if it’s the only thing running in your planted tank’s room.

However, from what I have learned while using this unit, this only happens if you over-tighten it.

This is somewhat confirmed by other reviewers online.

The only real noise I agree it makes is when you turn it on or off.

Otherwise, it reliably turns on and off as per the schedule if on a timer.

By the way, if you find the noise bothersome, you can use plumbing tape to get rid of it (not a troublesome “upgrade”).

One drawback I have to point out is that the water in the bubble counter drains after some weeks so you have to refill it.

This regulator is one stage, which can be expected at this price point, but I wouldn’t say that you should wait to accumulate a higher budget and save up for a dual-stage one.

The DoubleSun works perfectly fine and I’m very pleased with what I got for my money.

Buy this regulator if you don’t have deep pockets at the moment, and you’re okay with occasionally checking the pressure of the cylinder.

It’s an adequate purchase for a high-tech planted tank on a budget.

  • It is very affordable.
  • Easy to install.
  • It comes with a wrench and other essential installation tools.
  • Being compact, it takes up little space.
  • The noise during turning on or off may irritate or startle you if you are not used to such.
  • You have to refill the bubble counter after some weeks.
  • The bubble counter valve is rather over-sensitive, and it may take you time to tune it (once you get it right, it works well)

3. FZONE Aquarium CO2 Regulator Triple Stage – The design makes for safe and steady CO2 injections

Click here to see the current price + more photos on Amazon.

First, I like The Triple Stage FZONE Aquarium CO2 Regulator’s design and black color.

It’s simply nice and adds up to the cyberpunk look of your high-tech planted tank.

It is made of aluminium alloy and is sturdy and heavy enough, as far as quality goes.

To date, it is one of the best multi-stage CO2 regulators on the cheap side that I know of.

Due to its triple-stage design, it is well-composed enough to withstand turbo-charge pressure without ever breaking or releasing excess CO2 if things get out of control.

Its strength makes it suitable for smaller nano tanks with high-maintenance aquarium plant species.

It comes with an instruction manual to ease the work of setting up and further use.

The package includes all the necessary tools and kits as well.

This comprises 3 different wrenches (I simply call them spanners here at home).

This will save you from having to look for just the right fit elsewhere.

There are also spare O-rings with extra rubber.

If you went the DIY paintball cylinder road, worry not, for FZONE Aquarium CO2 Regulator Triple Stage also comes with a paintball adapter.

This makes it compatible with several cylinder models, from disposable CO2 cartridges to 20oz tanks.

There is also the solenoid, which remains cool even after running for hours.

The solenoid valve will shut off or turn on the moment the timer alerts it.

One of the best features of this unit is its needle valve which is considerably reliable and accurate.

The fine-tuning is a breeze, in my opinion.

The bubble counter is here too, and you can easily set it to count 3 or 5 bubbles per second.

You can read the pressure gauge without straining your eyes because it’s made clear, which I also like.

You are also probably going to love the fine-tuning knob.

With it, you can effortlessly set the output pressure anywhere from 0 to 60 PSI (pounds per square inch).

The surprise is that although this regulator has so much to offer, it remains relatively cheaper even compared to its dual-stage competitors.

Many suchlike models can cost way more.

Get this regulator for your aquarium’s pressurized CO2 system if you’d like to eliminate any possibility of the “end of tank dump” phenomenon while keeping inside a reasonable budget.

  • Triple stage pressure relief
  • Quality needle valve for the price
  • Very budget friendly
  • It can be used for vertical or horizontal tanks because it rotates.
  • It comes with an easy-to-understand instruction manual.
  • It is made from durable materials.
  • It has all the components you can need for a CO2 regulator.
  • It consumes less power compared to other models of its class.
  • The pressure gauge is easy to read.
  • At times, the bubble counter may leak, based on verified reports from some of my friends.
  • Has some negative feedback on Amazon, but that’s mainly because of poor handling of the delivery (not the product’s fault, and you can always return it and either get refunded or demand for a replacement)

4. S.T. International Professional CO2 Regulator – Durable with Unique Magnetic Solenoid Valve

Click here to see the current price + more photos on Amazon.

The S.T. International CO2 Regulator comes with a 2-year warranty.

I’m aware that this guarantee means a lot to a number of people so the earlier I point it out, the better.

I think, that it somewhat amplifies the fact that the regulator is made to last.

This CO2 regulator comes without an instruction manual, but the whole assembly process is pretty much care-free.

Adjusting bubbles might require a good finger and eye coordination but not for so long.

Once you strike the mark, it remains stable.

I recommend this CO2 regulator if you want the best for your larger, heavily planted aquarium.

The pressure is put under control by the reliable output-pressure valve and aquatic plants will receive steady CO2 injections even in your absence.

It’s important to me to mention that all these occur quietly and without the regulator catching heat.

Anyway, the pressure gauge uses a mixture of colors that some users find difficult to navigate, though I don’t think it’s a big deal.

It comes with a magnetic solenoid valve, first designed and patented by S.T. International, the manufacturer of this unique regulator.

I have noted the solenoid has no indicator light, but it reliably turns the regulator on and off as programmed.

This unit undoubtedly has the best solenoid on this list.

Again, CO2 doesn’t burst forth like a flood when the timer turns it on in the morning, as happens with some models that I can’t recommend any day.

One thing I need to mention is that despite the price tag, this unit does not come with a two-stage pressure relief.

However, the product works as advertised and EOTD events happen rarely, and to rather neglected systems anyway.

It’s pretty obvious that if you’re going for a CO2 regulator of this caliber you’ll be looking after a high-tech aquarium with demanding plants that would require your attention either way.

Just monitor the pressure of the bottle and refill when appropriate.

Finally, this regulator is compatible with various cylinder models.

Get this CO2 regulator if you’re willing to pay a little more but will value the durability of the equipment you get in return.

The emphasis here is on durability and quality.

  • It comes with a 2-year warranty.
  • This robust regulator is made to last long.
  • It’s compatible with various cylinder models, including disposable cartridges.
  • It is not noisy.
  • The CO2 flow-rate is easy to adjust once you have calmed your hands.
  • The solenoid magnetic valve design helps to minimize energy consumption.
  • Minimized energy usage also means there is no excess heat.
  • The rainbow colors on the gauges make it somewhat difficult for some people to read the pressure.
  • It comes without manual (though setting it up is a no-brainer)
  • Pricier

Is Paying Less For A Cheap One Worth It?

There is this deep-seated notion lurking in a buyer’s mind that if the product is cheap, it means it is substandard, not genuine, not capable enough, is faulty and so forth.

All I can say is that it depends on what product you are buying.

There are indeed times when cheap is expensive.

Here is the fact about cheap aquarium CO2 regulators:

Different models of aquarium CO2 regulators tend to be the same in terms of essential functionalities whether the price is cheap or expensive. There is not much difference between costly ones and inexpensive ones when it comes to serving their purpose. However, the expensive ones usually have additional features to make the work easier and are also made of high-quality more durable parts.

If you feel you need to benefit from these extras, then paying a higher price will be perfectly justified.

The cheaper ones will still perform effectively upon proper maintenance but the advanced ones are more efficient and will come with a warranty and extended durability.

Tips To Boost the Growth in Your Planted Tank Further

Well-programmed CO2 injections are not necessary for a planted aquarium, however, definitely speed up the growth processes of aquatic plants and give the benefit of more vivid coloration.

If you wish to see your aquarium plants look healthy and happy in a high-tech setup you will want to have a CO2 system set in place.

However, that is just part of the strategy.

Just as you cannot thrive on oxygen alone no matter how important it is, so can’t expect the plants progress well solely on regular CO2 supply.

So here are some other tips to help you improve the growth in a planted tank:

  • Ensure the plants have adequate lighting. After all, they only utilize the CO2 alongside light. The two virtually go hand in hand. Your choice of aquarium lighting should provide the correct light spectrum for plant growth alongside adequate intensity and water penetration of the beam. I have a very detailed guide on the best planted tank LED fixtures that fall within these criteria to help with making sure that your aquarium plants will thrive.
  • Supply essential nutrient elements to the plants via fertilizers. In a closed environment such as a home fish tank you simply can’t provide all the building blocks that lush plants would require to grow in a high-tech setup. You’ll need to understand macro and micronutrients and also recognize which of these (if not both) do aquarium plants need. I can help you choose the best aquarium plant fertilizer for your setup.Visit the link to go in-depth on that.

  • Lay a suitable substrate for anchorage and additional fertilization. This is pretty much self-explanatory, as it functions similarly as with land-based vegetation. However, if you don’t know the difference between an inert and a soil substrate I recommend that you pay a visit to my guide on planted tank substrates. There you’ll learn how to combine these for better aesthetic and growth results, how to spot false advertising and which will work best for your future high-tech setup.

Over To You

Choosing the right equipment will save you tons of anxiety for the lives of your aquatic plants and fish.

Also, remember that a solenoid valve is a must-have if you want the regulation to time itself as you mind your own business.

At the end of the day, you want to see your planted aquarium flourish and one of the best ways to achieve that is by engaging a suitable CO2 regulator.

I’d like to believe that this article has, to whichever extent, boosted your technological knowledge on the subject.

Drop me a comment below if you have any questions or can’t decide on a piece of equipment.

Sharing is caring!

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Notify of